Abstract: To investigate effects of non-tillage on N₂O and CO₂ emmissions in the North China Plain,a field experiment was conducted to measure N₂O and CO₂ emiisions from soil under conventional tillage and soil that had just assumed non-till-age practice,using close chamber technique and gas chromatography during the maize growing season.Cumulative N₂O emission from the non-tillage soil was 0.31 kg·hm^-2,just slightly higher than from the tilled soil,being 0.27kg·hm^-2.In contrast,non-tillage significantly increased soil CO₂ emission by 41.6% compared to tillage(1333kg·hm^-2).N₂O emission peaks appeared after irrigation,heavy rainfall or consecutive cloudy days.N₂O emission peaks in the non-tillage treatment ranged from 28.1 to 38.4 μg·m^-2·h^-1,which were greater than those in the tillage treament (18.6-25.7 μg·m^-2·h^-1).N₂O and CO₂ fluxes in the two tillage systems displayed a significant exponential relationship with soil temperature,and the seasonal variation of N₂O and CO₂ fluxes could be better explained by soil temperature in tilled soil than in non-tilled soil.

Key words: nitrous oxide, carbon dioxide, non-tillage, greenhouse gas, North China Plain, fluvo-aquic soil